M998 won’t start after fuel filter change?

[mhoge]

I'm doing something wrong here. Worse, not the first time I've done it.
I followed the TM (20-2, page 3-60, section 3-32), try to crank a lot, but it won't start. Did crack the injectors too. Thinking about possible solutions that avoid a tow to the local mechanic. Trying not to kill my batteries like last time, did not have a good experience with the last shop that fixed it. 3 week wait and tore it up too.

Question #1: My first problem could be I did not refill the fuel filter when I put it back on, so it needs to be completely refilled? I feel like the answer will be "duh, obviously."

Question #2: Is there a way to prime the fuel system, like with a fuel priming bulb to refill it with fuel? Would the bleed opening be the best place for this?

 

[Coug]

The lift pump moves a lot of fuel, so as long as the fuel line going to the injection pump is cracked a little it should self bleed provided there are no other issues.

Something to test.
There is a drain valve for the fuel filter up in the front wheel well.
When you are cranking over the engine open that valve and see if fuel comes out.
If fuel comes out it's likely either air that isn't bleeding from the system, or maybe something wrong with the injection pump, or possibly you screwed something up with the fuel lines. It also tells you that your fuel lines up to the filter are good and the lift pump is working properly.

If no fuel comes out your lift pump is failed and needs replaced. These engines will run with a failed lift pump until you introduce air into ths system by cracking a line or replacing the filter.

 

[87cr250r]

You said you cracked the injectors. If you have fuel there the engine will run. If it's still not starting I would be looking at glow plugs.

 

[Mogman]

Have you removed the two check valves in front of the fuel tank? they are problematic and most just remove them.
Was it running OK before you changed the filter? if not the lift pump could also be bad, the engine will usually run but not well with a bad lift pump but the pump in the IP will not be able to prime the lines, check valves would be the first thing to check.
You need to make sure you are getting fuel to the filter drain before worrying about cracking the injector lines.
You can LIGHTLY pressurize the tank with an air hose but only a couple PSI or so or you can cause many other problems.
AGAIN check those check valves!

 

[mhoge]

If no fuel comes out your lift pump is failed and needs replaced. These engines will run with a failed lift pump until you introduce air into ths system by cracking a line or replacing the filter.

Have you removed the two check valves in front of the fuel tank? they are problematic and most just remove them.
Was it running OK before you changed the filter? if not the lift pump could also be bad, the engine will usually run but not well with a bad lift pump but the pump in the IP will not be able to prime the lines, check valves would be the first thing to check.
You need to make sure you are getting fuel to the filter drain before worrying about cracking the injector lines.
You can LIGHTLY pressurize the tank with an air hose but only a couple PSI or so or you can cause many other problems.
AGAIN check those check valves!

I'm going to give those check valves a good look, but now confident the lift pump is the main problem here. It ran OK until I opened the fuel system up.
I checked the inlet line to the filter while cranking a few times, nothing came out even with the filter cup filled. Pretty sure the LP has been bad all this time and I've somehow gotten by.

 

[Mogman]

A stuck check valve gives the same symptoms as a bad lift pump, hopefully that is the issue, much easier to deal with, you just need some 3/8 and 5/16 fuel hose, of course don't get them crossed.
Do remember if you pull the lift pump you have to pull the plate directly behind the pump and remove/grease/and re-install the pump rod, so buy that gasket also.

 

[blutow]

If the lift pump age isn’t known, it’s a good component to proactively replace on these trucks in my opinion. Like anything w rubber components, they are prone to aging out even with minimal running time. Certainly look at the check valves as well, but consider replacing the lift pump regardless. Pretty inexpensive and not too hard to swap.

 

[mhoge]

So, unless I'm looking in the wrong spot I do not have the check valves on the supply and return lines. It's possible the previous guy who owned it removed them.
Ordered a new pump and back plate gasket already, going to be a not so great time with the tight space and splashguard removal. It was much easier to swap the pump out on my M151.

 

[blutow]

going to be a not so great time with the tight space and splashguard removal

I did the pump on my 1123 without removing the splash guard. It was a pain, but doable.

 

[Mogman]

EVERYTHING is easier to do on a M151!!
Yes it is entirely possible the valves have been removed, they are/were inline between the fuel tank steel lines and the steel lines going to the lift pump.